The Cell Biology Core for this program project has been established in order to centralize highly used techniques for tissue processing, immunostaining, microscopy, imaging, and real time PCR for the four investigators. This is expected to result in increased efficiency, reduced cost and improve reproducibility. The Core will be located within the recently renovated Morphology Laboratory of the Center for Organogenesis at the University of Michigan. The Core is centrally located with respect to all of the investigators, and conveniently close to Dr. Gumucio, who acts as the Core Director. A full time Core Technical Director with excellent background in gastroenterology, and with technical expertise in histology, immunohistochemistry, imaging and embryo dissection has been identified. The Core Director and Technical director will meet monthly with the three other Principal Investigators to report progress for the past month and to set priorities for the coming month. The Cell Biology Core will consist of four substations, including: an Embedding/Immunohistochemical Substation (for paraffin or OTC embedding, sectioning, staining and immunostaining), a Flow Cytometry substation (for assistance with flow analysis, performed in another University Facility), a Microscopy Substation (for image capture, image analysis, and for assistance with Laser Capture Microdissection, done at another University Facility), an RNA and Real Time PCR Substation (for assistance with embryo dissection, RNA preparation and real time PCR analysis). The goals of the Cell Biology Core are:1. To provide high quality service to the investigators in a rapid and efficient manner. 2. To provide technical support to the investigators with a commitment to teaching techniques, e.g., immunohistochemical, flow cytometry, real time PCR, Laser Capture Microdissection. 3. To provide the reagents necessary to do morphologic, histologic, image and PCR analysis. A number of reference books, owned by the PROGRAM PROJECT GRANT investigators, will be placed in a common area of the Cell Biology Core to facilitate rapid investigation of questions and problems that could be encountered.